This invention relates to apparatus for preparing a cup of hot drink such as juice or soup by uniformly mixing a powder with hot water.
FIG. 1 shows a conventional hot drink preparing apparatus, in which a water supply pipe 6 is connected at its one end to a water source such as a city water source through an electromagnetic valve 5 and at the other end to the bottom of a water tank 1. A heater 4 for heating water is disposed in the lower portion of the tank 1, and a heat sensing member 3a of a thermostat 3 is disposed above the heater 4. A float 8 is disposed on the water surface in the tank 1. The float 8 is connected to a micro-switch 7 arranged on the exterior of the tank and the switch 7 is connected to the electromagnetic valve 5 to control the switch so as to constantly maintain the water level in the tank 1. A hot water feeding pipe 9 is connected to the upper portion of the tank and the free end of the pipe 9 is directed to a receptacle 16 through an electromagnetic valve 10 for adjusting the amount of the hot water to be poured into the receptacle 16.
A measuring device 14 for measuring a powder is attached to the bottom of a hopper 13 filled with the powder to be mixed with the hot water. A chute 15 is connected to the measuring device 14 and the front end opening of the chute 15 is directed toward the receptacle 16. A mixer 18 provided with stirring wings 19 driven by a motor 17 is connected to the bottom of the receptacle and a pipe 20 is connected to the bottom of the mixer 18 and extends downwardly towards the opening of a cup 21 disposed below the mixer 18.
Heretobefore, a cup of hot drink has been prepared by using the apparatus described above in the following manner.
Water supplied to the tank 1 from the water source through the pipe 6 is adjusted by the float 8 so as to maintain a constant water level. The water in the tank 1 is heated by the heater 4 and the temperature of the heated water is controlled by the thermostat 3. A predetermined amount of the powder 12 is measured by the powder measuring device 14 and fed into the receptacle 16. When the powder 12 is fed, the electromagnetic valve 10 is opened for a predetermined time to pour the hot water in the tank 1 into the receptacle 16 through the pipe 11. The powder 12 and the hot water in the receptacle 16 is then fed to the mixer 18 and stirred by the stirring wings 19 so as to completely dissolve the powder into the hot water, and thereafter, the mixed hot drink is poured into the cup 21 through the pipe 20.
However, in the conventional hot drink preparing apparatus, the hot water, the powder or the hot drink contact the receptacle, the mixer or the pipe 20, so that if the apparatus has not been used for a certain interval, the quality or taste of the powder or the hot drink adhered to the inside surfaces of these members may be changed and bacteria are likely to be grown, thus not only becoming insanitary but also damaging the taste of the hot drink to be prepared next. Furthermore, the hot drink adhered to the inside surfaces of these members drops from the front end of the pipe 20 after pouring the hot drink and closing the electromagnetic valve 10. It may be called "after-dribble" which will contaminates the outlet opening of the pipe 20.
There has been proposed another apparatus, for eliminating the defects mentioned above, in which the receptacle 16 is provided with a pipe for supplying a small amount of water to the pipe 20 to clean the inside surface thereof every time when the hot drink is poured into the cup 21. However, in such apparatus, it is not always possible to completely clean the pipe 20 so that it will be gradually contaminated during the use over a long time, and the "after-dribble" cannot be avoided. Furthermore, since one cleaning process is added every time when one cup of hot drink is prepared, not only additonal time is required to pour the next hot drink, but also the apparatus is complicated, so that it takes much time and cost to periodically disassemble and clean the apparatus.
Additionally, in the conventional apparatus, although the water level in the tank 1 is controlled by the float 8, even if the water level is preset to the predetermined level when water is supplied into the tank 1, the level will be raised when the water is heated and expanded. Therefore, in a case where the water level is closely related to the time when the electromagnetic valve 10 is opened, it is impossible to pour always a predetermined amount of hot water and to obtain a cup of hot drink with desired consistency, thus damaging the taste of the hot drink.
Furthermore, since the hot drink is poured through the receptacle 16, the mixer 18, and the pipe 20, the temperature of the hot water fed from the pipe 11 may considerably lower before it is poured into the cup, or change every time when the hot drink is poured because these members are gradually wormed by passing the hot drink.
The powder 12 in the hopper 13 is fed into the receptacle 16 after measuring the amount of powder necessary for preparing one cup of hot drink by the measuring device 14. Conventionally, as the measuring device, there was used, for example, a turn-table type measuring device provided with a plurality of measuring cups. However, in the use of such a device, it was considerably difficult to accurately measure the predetermined amount of the powder and the device itself was more complicated. In order to eliminate such defects, there has been proposed a measuring device having a two-stage shutter mechanism which is compact and has good measuring accuracy in comparison with the former type measuring device.
One typical example of the measuring device of this type is shown in FIG. 4, which comprises a measuring cylinder 43 having a predetermined inside volume and connected to the bottom of the hopper 13, upper and lower shutters 44 and 45 arranged respectively to close and open the upper and lower end openings of the measuring cylinder 43, and a mechanism for horizontally driving these shutters. A chute 15 is connected to the lower end opening of the cylinder 43.
As shown in FIG. 4, the upper and lower shutters 44 and 45 are provided with openings 44a and 45a, respectively, each having a diameter D which is substantially equal to that of the upper or lower end opening of the cylinder 43, and one ends of these shutters are connected together by a connecting portion. A female screw 48 is fixed to this connecting portion and the female screw 48 engages a feed screw 47 which is driven by a reversible motor 49. This shutter mechanism operates to alternately open and close the upper and lower shutters in the following manner. In a first stage, the lower shutter 45 is positioned to close the lower end opening of the measuring cylinder 43 and the opening 44a of the upper shutter 44 is alined with the upper end opening of the cylinder. In this state, the powder 12 fills the measuring cylinder 43. Then, the motor 49 operates to rotate the feed screw 47 to leftwardly move the shutters 44 and 45 by the distance D, thus closing the upper end opening of the cylinder 43, while closing the lower end opening thereof. After measuring the powder contained within the cylinder, the motor further moves to leftwardly the shutters by the distance D so that the opening 45a of the lower shutter 45 will be alined with the lower end opening of the cylinder 43, while the upper end opening thereof is closed. Thus, the predetermined amount of the powder in the cylinder is discharged to the chute 14. After the predetermined amount of the powder has been discharged, the motor 49 is reversely rotated to return the shutters 44 and 45 to the original position shown in FIG. 4, and the measuring cylinder 43 is again filled with the powder 12.
However, in this conventional shutter mechanism, each shutter 45 and 45 must be moved at least by the distance 2D, so that it is required for the shutter to have a length larger than the length 3D. Therefore, a large-size measuring device 14 is needed and the apparatus itself occupies a considerably large space. Furthermore, since the shutters are moved over a distance larger than 2D, it has a considerably large area which contacts directly the powder, so that the powder 12 may enter into the shutter mechanism during the sliding movement of the shutters, and the sliding resistance of the shutters will be increased. In another respect, it is difficult to increase the moving speed of the shutters where a feed-screw type shutter driving mechanism is used and there is a fear that the powder adheres to the feed screw 48 to disturb the smooth engagement of the feed screw 48 with the female screw 47. Although the motor 49 and the feed screw mechanism may be substituted by a pneumatic cylinder-piston assembly or a hydraulic cylinder-piston assembly to easily and speedily drive the shutter mechanism, and extra driving source is needed therefor. Furthermore, in a case where the upper and lower shutters are constructed so as to be independently driven, two separate driving sources are required and a mechanism for controlling the timing for driving the shutters is also required.